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PET/CT因其高灵敏度、可视化、定量精确和非侵入性等特性,已成为临床重要的影像技术,广泛应用于癌症的诊断和治疗评估[1]。18F-FDG是临床PET/CT应用最为广泛的显像剂,能够探测葡萄糖代谢异常情况。然而,18F-FDG PET/CT的特异度较低,且常常难以正确区分生理性与病理性摄取。此外,18F需要通过加速器生产,对于大部分医院来说,获取和维护一个正常运转的回旋加速器的成本太高[2]。
在正电子核素显像中,68Ga具有优良的性能,其可以通过68Ge-68Ga发生器淋洗获得,获得途径较简便且成本相对较低。母体核素68Ge的半衰期为270.8 d,所得子体核素68Ga的半衰期为67.7 min,68Ga的正电子衰变能量占其所有衰变能量的89%,仅次于11C和18F。另外,68Ga的半衰期适中,较为适于实际使用。与11C(半衰期为20.3 min)相比,对68Ga进行化学合成和注射扫描有较为充裕的时间,其放射性活度不会迅速降低。相比于18F标记显像剂,68Ga标记显像剂具有标记方法简单、反应时间短、纯化技术简便等特点,由于68Ga标记的多为多肽分子,标记产物的特异性更好,通常具有更好的显像质量和更高的靶向性。目前,68Ga标记显像剂已经广泛用于去势抵抗性前列腺癌、神经内分泌肿瘤等恶性肿瘤的临床诊断、疗效评估和肿瘤分期[3-6]。
目前,国内68Ge-68Ga发生器的使用仍依赖进口,尚无国产的68Ge-68Ga发生器投入使用。我们自主研发了国产68Ge-68Ga发生器,用其进行标记前列腺特异性膜抗原(prostate-specific membrane antigen,PSMA)-11的可行性研究和动物体内显像实验,并与进口68Ge-68Ga发生器进行了初步对比。
国产68Ge-68Ga发生器的制备及初步应用评价
Preparation and preliminary application evaluation of a domestic 68Ge-68Ga generator
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摘要:
目的 制备国产68Ge-68Ga发生器,通过与进口68Ge-68Ga发生器(德国ITG公司)进行对比,对其进行初步应用评价。 方法 制备68Ge-68Ga发生器,测定其淋洗后初始时间(0)、1、4、12 h的淋洗产物68Ga3+的放射性活度;与进口68Ge-68Ga发生器淋洗产物68Ga3+ 的γ能谱及68Ga3+在正常小鼠体内的分布情况进行对比;确定国产68Ge-68Ga发生器淋洗产物标记前列腺特异性膜抗原(PSMA)-11的最佳标记条件及产物的放射化学纯度;对比国产与进口68Ge-68Ga发生器淋洗产物标记的68Ga-PSMA-11在22Rv1前列腺癌肿瘤模型小鼠体内的分布情况。计量资料的组间比较采用LSD法进行检验。 结果 国产68Ge-68Ga发生器在淋洗后初始时间(0)、1、4、12 h的淋洗产物68Ga3+的放射性活度分别为125.8、74.0、118.4、111.0 MBq。国产与进口68Ge-68Ga发生器淋洗产物68Ga3+的γ能谱高度一致,在正常小鼠体内的分布基本没有差异,均在心脏呈现放射性高摄取。国产68Ge-68Ga发生器淋洗产物标记PSMA-11的最佳标记条件是pH值4.5,85℃恒温反应15 min,得到的68Ga-PSMA-11的放射化学纯度>95%。国产与进口68Ge-68Ga发生器淋洗产物标记的68Ga-PSMA-11在22Rv1前列腺癌肿瘤模型小鼠体内的显像结果显示,68Ga-PSMA-11均在肿瘤部位呈现高摄取,其余主要分布于肾脏和膀胱。国产68Ge-68Ga发生器淋洗产物标记的68Ga-PSMA-11注射后30、60、90 min,肿瘤部位的放射性摄取值均低于进口68Ge-68Ga发生器[(3.60±0.14) %ID/g对(5.30±0.42) %ID/g、(3.40±0.12) %ID/g对(5.90±0.36) %ID/g、(2.90±0.28) %ID/g对(5.50±0.33) %ID/g],且差异均有统计学意义(LSD法,均P<0.05)。 结论 国产68Ge-68Ga发生器淋洗产物68Ga3+及其标记的68Ga-PSMA-11在正常小鼠和肿瘤模型小鼠体内的分布情况与进口68Ge-68Ga发生器无明显差异。 -
关键词:
- 放射性核素发生器 /
- 锗 /
- 镓放射性同位素 /
- 前列腺特异性膜抗原 /
- 正电子发射断层显像术 /
- 体层摄影术,X线计算机
Abstract:Objective To prepare a domestically produced 68Ge-68Ga generator and compare it with an imported 68Ge-68Ga generator (ITG Company, Germany) for preliminary application evaluation. Methods A 68Ge-68Ga generator was prepared, and the radioactivity of its elution product 68Ga3+ was measured at the initial time (0) and 1, 4, and 12 h after elution. The γ-spectra of the elution product 68Ga3+ and its distribution in normal mice were compared with those of an imported 68Ge-68Ga generator. The optimal labeling conditions for prostate-specific membrane antigen (PSMA)-11 labeled by domestic 68Ge-68Ga generator elution product and the radiochemical purity of the labeled product were determined, and the distribution of 68Ga-PSMA-11 labeled by domestic and imported 68Ge-68Ga generator elution products in 22Rv1 prostate cancer tumor model mice was compared. The intergroup comparison of measurement data was conducted using the LSD method. Results The radioactivity values of 68Ga3+ in the elution product of the domestic 68Ge-68Ga generator at the initial time (0), 1, 4, and 12 h after elution were 125.8, 74.0, 118.4, and 111.0 MBq, respectively. The γ-spectra of 68Ga3+ eluted by domestic and imported 68Ge-68Ga generators were highly consistent, and no difference was observed in the distribution of 68Ga3+ in normal mice, and both showed high uptake of radioactivity in the heart. The optimal labeling conditions for PSMA-11 labeled by domestic 68Ge-68Ga generator elution product were pH 4.5, reaction at 85 ℃ for 15 min, and the radiochemical purity of the product 68Ga-PSMA-11 was >95%. The imaging results of 68Ga-PSMA-11 labeled by domestic and imported generator elution products in 22Rv1 prostate cancer model mice showed high uptake of 68Ga-PSMA-11 at the tumor site, while the rest were mainly distributed in the kidneys and bladder. At 30, 60, and 90 min after injection, the radioactive uptake values of 68Ga-PSMA-11 labeled by the domestic 68Ge-68Ga generator were lower than those of the imported 68Ge-68Ga generator ((3.60±0.14) %ID/g vs. (5.30±0.42) %ID/g, (3.40±0.12) %ID/g vs. (5.90±0.36) %ID/g, (2.90±0.28) %ID/g vs. (5.50±0.33) %ID/g). The differences were statistically significant (LSD method, all P<0.05). Conclusion No significant difference was observed in the distribution of 68Ga3+ and its labeled 68Ga-PSMA-11 in normal mice and tumor model mice between the domestic 68Ge-68Ga generator and the imported 68Ge-68Ga generator. -
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